1. Technical Field
The technology disclosed herein relates to a lens barrel that supports an optical system.
2. Background Information
There are known lens barrels that support an optical system with which the focal distance can be varied. For example, the lens barrel disclosed in Japanese Laid-Open Patent Application 2007-219304 comprises a first moving cam ring in which a cam groove is formed, and a first group lens barrel that supports a first lens group. The first group lens barrel has a follower pin that engages in the cam groove. With this lens barrel, the first moving cam ring and the first group lens barrel allow the first lens group to be moved in the optical axis direction with respect to the first moving cam ring.
A cam mechanism featuring a cam follower and a cam groove is employed in this type of lens barrel. For example, the cam mechanism has three cam followers and three cam grooves. The cam followers are guided in the cam grooves, so that the two frame bodies more relatively in the optical axis direction. To achieve a higher zoom ratio, it is preferable to lengthen the distance that the two frame bodies move relatively in the optical axis direction.
However, to lengthen the distance that the two frame bodies move relatively in the optical axis direction, the lengths of the two frame bodies in the optical axis direction have to be increased, so if an attempt is made to increase the zoom ratio, the lens barrel ends up being larger in the optical axis direction.
It is an object of the technology disclosed herein to provide a lens barrel with which the zoom ratio can be increased while minimizing the increase in size.